Bending machine for creating bends to the left and right

ABSTRACT

A machine and method for bending tubes of large diameter in different bending directions, wherein a tube ( 10 ) is guided in the axial direction through an annular inductive heating device ( 7 ); the tube ( 10 ) is secured by a bending lock ( 4 ) at the end ( 11 ) thereof intended to be bent; at least one bending arm ( 2 ), which is mounted rotatably about a vertical axis of rotation ( 8 ), is located at the part of the bending machine that is disposed in the advancing direction of the tube ( 10 ); the bending lock ( 4 ) is indirectly connected to the bending arm ( 2 ); the bending lock ( 4 ) has a force transmission device between the receiving device for tubes and the bending arm ( 2 ); and the force transmission device is connected to the bending arm ( 2 ).

The invention relates to a device and a method for bending tubes in the bending machines, where the tubes to be bent are heated inductively at the bending location. The tubes are often thick-walled tubes with wall thicknesses of 3 to 120 mm and with large diameters of 50 to 1060 mm and weights of several tons. Correspondingly large and heavy are the tube bending machines that are developed for this purpose. These can typically realize bending radii of 0.1 to 10 meters.

For each bending procedure, the straight end of the tube to be bent must be clamped in a feeding carriage while a so-called bending lock is attached to that end that is to be bent. An annular device for inductive heating, typically also referred to as an induction ring is located between the bending lock and the feeding carriage.

Due to the effective large forces that need to be taken up, bending locks often have a very bulky design and take up a lot of space. DE 10 2007 022 004 A, for example, describes a relevant device. In this case, the bending lock is mounted on a bending arm, and the beading arm can rotate around a vertical rotational axis.

Often, tubes must be bent several times in different directions. This allows for achieving complex curvatures or, for example, S-shaped or serpentine tube geometries that can be manufactured very precisely under controlled conditions with such tube bending machines, which otherwise would only be possible at the future place of installation by using pipe fittings and welds and with limitations in the attainable precision.

Tube bending machines of the prior art can perform such bending steps in succession to some degree, however, if the desired pipe shape requires that the bending direction changes between two successive bending steps, significant installation work is required between the bending steps. In other words, the entire bending lock together with the bending arm must be disassembled and re-assembled each time and aligned at the mirror-inverted side of the tube to achieve this purpose. Or, the tube to be bent must be removed from a left-bending machine and fed into an additional machine, a right-bending machine. This causes geometric inaccuracies that can be eliminated only with significant effort.

For example, DE 25 13 561 A 1 presents a machine with a small and a large bending arm, rotating one time to the right and one time to the left. To be able to utilize this system for spatial bends, the tabs must be removed from the right-rotating side of the machine and re-clamped and positioned in the left-rotating side. This is associated with significant time expenditure and leads to inaccuracies.

DE 100 60 605 A 1 presents left- and right-rotating bending heads; however, due the fact that the bending heads are located one above the other, the sand of the tube must travel all the way down in order to get to the second bending head.

Since both of the tubes to be bent and the equipment component of the bending lock and the bending arm are very heavy, significant effort and care must be exercised when operating the lifting devices in order to avoid any damage during the installation work and to prevent uncontrolled changes in the position of the tube to be bent. Such installation work can take several hours and restrict the throughput due to the bending steps at the bending machines.

It is, therefore, the objective of the invention to provide an economic method, where such installation work can be reduced to a minimum, thereby significantly increasing the throughput of such bending machines when used for making multiple bends.

The invention achieves this objective with a device for bending tubes of large diameters, in different directions, wherein

-   -   in this bending device a tuba is guided in the axial direction         through an inductive heating device that surrounds this tube in         annular fashion,     -   the tube is clamped at the end that is to be bent by a bending         lock,     -   at least one bending arm that is supported in a rotating fashion         around its vertical rotational axis is located at the part of         the device for bending and is situated in the feeding direction         of the tube,     -   the bending lock is connected indirectly to the bending arm,     -   the bending lock exhibits a force transfer device between the         take-up device for tubes and the bending arm,     -   the force transfer device is connected to the bending arm in an         adjustable manner such that the distances between the center         axis of the take-up device for tubes and the vertical rotational         axis can be selected between a minimum and a maximum distance,         which allows for setting a range between a maximum and minimum         bending radius,     -   the device exhibits at least one additional bending lock with         one additional bending arm, a take-up device for tubes and a         force transfer device for bending forces from the take-up device         to the additional bending arm,     -   whereby the direction of rotation of the additional bending arm         is opposite to the direction of rotation of the first bending         arm, and     -   each of the two bending arms can be moved parallel to each other         and perpendicular to the feeding direction of the tubes to be         bent.

The result of using two movable bending arms with bending locks is that for right rotations and for left rotations the respective vertical rotational axes of either the one or the other bending lock is used, while the respective other bending lock which is not needed is moved out of the pivoting area. Thus, the expensive installation work is not needed at all.

The invention accomplishes this objective by a method for bending tubes of large diameters that is matched to the device, by

-   -   clamping the tube in a first bending lock that is connected to a         first bending arm that can be rotated around a first rotational         axis,     -   a second bending lock being moved away from the pivoting area of         the tube against the rotational direction and in the         perpendicular direction to the feeding direction of the tube to         be bent,     -   then bending a first section of the tube by advancing the tube,     -   declamping the tube from the first bending lock while securing         the tube,     -   moving the first bending lock from toe pivoting area of the tube         in perpendicular direction to the feeding direction of the tube         to be bent,     -   moving the second bending lock into the pivoting area of the         tube,     -   clamping the tube to be bent in the second bending lock, and     -   then bending a second section of the tube by advancing the tube.

During the change of the bending direction, the tube remains in an absolutely fixed position through being clamped in the feeding carriage.

In additional embodiments of the method according to the invention tube movements are carried out between the individual bonding steps. In those steps, the tube may be rotated around the center axis of the tube or advanced longitudinally. In this manner, numerous bending steps can be carried out in succession.

The invention will be explained in greater detail below based on FIGS. 1 to 4 e.

FIG. 1 shows an isometric drawing of a double bending machine;

FIG. 2 shows a top view.

FIG. 3 shows a front view.

FIGS. 4 a to 4 e show a top view of the individual procedures during multiple bending of a tube.

FIGS. 1 to 3 show such a double bending machine 1 with the two bending arms 2 and 3 and the bending locks 4 and 5. The tube to be bent (not shown) is located on the feeding carriage 6 and is pushed through the induction ring 7, wherein either the bending loch 4 or the bending lock 5 grips the tube and bends it around the rotational axis 8 or the rotational axis 9.

FIG. 4 shows the steps for an S-shaped bend of a tube 10.

FIG. 4 a shows the initial state. The tube 10 is located in the feeding carriage 6; its front tube end 11 is pushed through the induction ring 7 and is held by the bending lock 5. The bending arm 3 is thus positioned such that the desired bending radius 12 can be set and the bending arm 2 is moved out of the pivoting area.

FIG. 4 b shows the end of the first bending step, in this case a 135-degree bend.

FIG. 4 c shows that the bending lock 5 has been removed and the bending arm 3 has been moved away and that an advance by the feed length 13 has occurred.

FIG. 4 d shows that the bending arm 2 has been positioned such that the bending radius 14 can be set and that the bending lock 4 secures the tube 10. The bending arm 3 remains in its position out of the pivoting area.

FIG. 4 e shows the result of the second bending procedure, in this case a 135-degree bend that is exactly opposite to the first bend.

It is also apparent that many other spatial bending steps can be carried out in this manner without the need to disassemble the workpiece or one of the bending arms for this purpose, which saves considerable set-up time compared to the prior art and thus increases the turnover of the machine in a positive economical manner.

LIST OF REFERENCE CHARACTERS

1 Double bending machine

2 Bending arm A

3 Bending arm B

4 Bending lock A

5 Bending lock B

6 Feeding carriage

7 Induction ring

8 Rotational axis A

9 Rotational

10 Tube

11 Front end of the tube

12 Bending radius A

13 Feed length

14 Bending radius B 

1. A device for bending tubes with large diameters in different bending directions, wherein a tube is guided in the axial direction through an inductively acting heating device that surrounds this tube in an annular fashion, the tube is secured with a bending lock at the end that is to bent, at least one bending arm that is supported in a rotating fashion around its vertical rotational axis is located at the part of the device for bending and which is situated in the feeding direction of the tube, the bending lock is connected indirectly to the bending arm, the bending lock exhibits a force transfer device between the take-up device for tubes and the bending arm, the force transfer device is connected to the bending arm in an adjustable manner such that the distances between the center axis of the take-up device for tubes and the vertical rotational axis can be selected between a minimum and a maximum distance, which allows for setting a range between a maximum and minimum bending radius, the improvement wherein: the device includes at least one additional bending lock with one additional bending arm, a take-up device for tubes and a force transfer device for bending forces from the take-up device to the additional bending arm, the direction of rotation of the additional bending arm is opposite to the direction of rotation of the first bending arm, and each of the two bending arms is movable parallel to each other and perpendicular to the feeding direction of the tubes to be bent.
 2. A method for carrying our several bending steps on pipes with a larger diameter, using a device according to claim 1, said method comprising the steps of: clamping the tube in a first bending lock that is connected to a first bending arm, which can be rotated around a first rotational axis, moving a second bending lock away from the pivoting area of the tube against the rotational direction and in perpendicular direction to the feeding direction of the tube to be bent, bending a first section of the tube by advancing the tube, while securing the tube, declamping the tube from the first bending lock, moving the first bending lock from the pivoting area of the tube in perpendicular direction to the feeding direction of the tube to be bent, moving the second bending lock into the pivoting area of the tube, clamping the tube to be bent in the second bending lock, and bending a second section of the tube by advancing the tube.
 3. A method as set forth in claim 2, wherein a rotation of the tube around the center axis of the tuba is carried out between two bending steps.
 4. A method as set forth in claim 2, wherein a longitudinal advance of the tube in the direction of the center axis of the tube is carried cut between two bending steps.
 5. A method as set forth in claim 2, wherein a multitude of bending steps is carried out in succession. 